(i) Field of the Invention
This invention relates to a one-way clutch having a drag strip or the like.
b) Description o f the Related Art
A sprag-synchronized one-way clutch is constructed inter alia of an outer ring having an annular inner wall, an inner ring having an outer wall concentrically disposed in relation to the inner wall, a plurality of sprags arranged in an annular space formed between these inner and outer walls, an outer retainer and inner retainer for holding these sprags at predetermined positions, and a ribbon spring for applying such force as maintaining the sprags in contact with the outer and inner rings.
In such a one-way clutch, fictional force applying means such as a drag strip is arranged between a driver ring, for example, the inner ring and the inner retainer so that rotation of the inner ring can be surely transmitted to the sprags even when the inner ring is abruptly accelerated or is driven at a high speed.
This drag strip is attached to the inner retainer the one-way clutch and, when the inner ring as driver ring is inserted, a central flat strip portion is flexed to contact the inner ring under predetermined force. The drag strip therefore transmits drag torque to in the order of the drag strip, the inner retainer and the sprags so that engagement of the one-way clutch is ensured while reducing wearing of the sprags.
One example of the construction of a sprag one-way clutch is illustrated in FIG. 3. A one-way clutch 10 is equipped with sprags 3, which are held by an outer retainer 4 and an inner retainer 5 both arranged between an outer ring and an inner ring 2. Designated at numeral 6 is a ribbon spring which acts to maintain the sprags 3 in contact with the inner and outer rings.
Numeral 20 indicates a drag strip, which is attached to the inner retainer 5 by hangers 23. A sliding main portion 21 is provided with bent portions 22 and is maintained in adequate frictional contact with the inner ring 2 under spring force. When the inner ring 2 idles in a direction indicated by arrow A, the drag strip 20 accordingly transmits drag torque in the order of the drag strip 20, the inner retainer 5 and the sprags 3 so that the sprags 3 are caused to turn in a direction indicated by arrow B. As a result, the sprags 3 are tilted toward an idling side and the contact pressure between the sprags 3 and the inner ring 2 is hence lowered. This can reduce wearing of the sprags 3 upon idling. When the inner ring 2 rotates in the opposite direction, the resulting frictional force which acts on the drag strip 20 is also reversed in direction. The inner retainer 5 therefore pushes the sprags 3 into up eight positions, thereby surely bringing the sprags 3 into full engagement with the inner and outer rings 2,1.
Only a conventional drag strip 20 and the inner retainer 5 are i illustrated in FIG. 4. FIG. 5 is a side view of a hanger 23 of the conventional drag strip, while FIG. 6 is a schematic view illustrating the state of attachment of the hanger 23 on the inner retainer 5. The hanger 23 is formed integrally with the sliding main body 21 and, when observed in cross-section together with the sliding main body 21, presents a turned square U shape. As is depicted in FIG. 6, the hanger 23 is attached to the inner retainer 5. Incidentally, numeral 51 indicates a sprag window formed in the inner retainer 5 to accommodate one of the sprags 3 therein.
In the case of such a drag strip, an end portion of the sliding main body 21 hits the inner wall of the inner retainer 5 whenever the one-way clutch is engaged or disengaged, as shown in FIG. 7. A portion indicated by arrow a in FIG. 7 is therefore caused to wear out, resulting in occurrence of corner-to-corner contact between an upper wall of the turned square U-shaped hanger 23, said upper wall being indicated at letter b, and an upper wall of the inner retainer 5. This leads to concentration of stress on a bent portion of the hanger, said bent portion being indicated by arrow c, so that the drag strip may be broken there.